linux-kernel - Re: [PATCH net-next 4/5] net: ethernet: ti: am65_cpsw: move am65_cpsw_put_page() out of am65_cpsw_run

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Message-ID: <20250218180340.GF1615191@kernel.org>
Date: Tue, 18 Feb 2025 18:03:40 +0000
From: Simon Horman <horms@...nel.org>
To: Roger Quadros <rogerq@...nel.org>
Cc: Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Jesper Dangaard Brouer <hawk@...nel.org>,
	John Fastabend <john.fastabend@...il.com>,
	Siddharth Vadapalli <s-vadapalli@...com>,
	Md Danish Anwar <danishanwar@...com>, srk@...com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	bpf@...r.kernel.org
Subject: Re: [PATCH net-next 4/5] net: ethernet: ti: am65_cpsw: move
 am65_cpsw_put_page() out of am65_cpsw_run_xdp()

On Mon, Feb 17, 2025 at 09:31:49AM +0200, Roger Quadros wrote:
> This allows us to re-use am65_cpsw_run_xdp() for zero copy
> case. Add AM65_CPSW_XDP_TX case for successful XDP_TX so we don't
> free the page while in flight.
> 
> Signed-off-by: Roger Quadros <rogerq@...nel.org>

Reviewed-by: Simon Horman <horms@...nel.org>

> ---
>  drivers/net/ethernet/ti/am65-cpsw-nuss.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/ethernet/ti/am65-cpsw-nuss.c b/drivers/net/ethernet/ti/am65-cpsw-nuss.c

...

> @@ -1230,9 +1230,6 @@ static int am65_cpsw_run_xdp(struct am65_cpsw_rx_flow *flow,
>  		ndev->stats.rx_dropped++;
>  	}
>  
> -	page = virt_to_head_page(xdp->data);
> -	am65_cpsw_put_page(flow, page, true);
> -
>  	return ret;

It seems that before and after this patch ret is always initialised to
AM65_CPSW_XDP_CONSUMED and never changed. So it can be removed.

Given that with this patch the function only returns after the switch
statement, I think this would be a nice follow-up.

diff --git a/drivers/net/ethernet/ti/am65-cpsw-nuss.c b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
index 20a4fc3e579f..4052c9153632 100644
--- a/drivers/net/ethernet/ti/am65-cpsw-nuss.c
+++ b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
@@ -1172,7 +1172,6 @@ static int am65_cpsw_run_xdp(struct am65_cpsw_rx_flow *flow,
 {
 	struct am65_cpsw_common *common = flow->common;
 	struct net_device *ndev = port->ndev;
-	int ret = AM65_CPSW_XDP_CONSUMED;
 	struct am65_cpsw_tx_chn *tx_chn;
 	struct netdev_queue *netif_txq;
 	int cpu = smp_processor_id();
@@ -1228,9 +1227,8 @@ static int am65_cpsw_run_xdp(struct am65_cpsw_rx_flow *flow,
 		fallthrough;
 	case XDP_DROP:
 		ndev->stats.rx_dropped++;
+		return AM65_CPSW_XDP_CONSUMED;
 	}
-
-	return ret;
 }
 
 /* RX psdata[2] word format - checksum information */

...